Question

why does the pulmonary vascular bed have less resistance than the systemic bed?

Answer 1

The pulmonary vascular bed includes blood circulation from heart to lungs and from lungs to the heart. Blood from right ventricle goes to the lungs through pulmonary artery and return to left ventricle through the pulmonary vein.

The vascular resistance increases with arterial pressure. The pressure defference (pressure gradient) between pulmonary arteries and the left atrium is approximately 10 mmHg which is approximately 10 times less in comparison to 100 mmHg pressure gradient in the systemic circulation. Therefore, pulmonary vascular bed resistance very less that is one-tenth of the resistance of systemic circulation.